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Kubernetes - open-source container orchestration system

Install Kubernetes on Ubuntu 22.04 machines or VMs in April, 2024​

This is a bit updated, brief note based on How to Install Kubernetes Cluster on Ubuntu 22.04 (Step-by-Step Guide). You should read it for much better, well-written explanation.

Update and upgrade Ubuntu [ALL]​

sudo apt update
sudo apt upgrade

Disable swap [ALL]​

sudo swapoff -a
sudo sed -i '/ swap / s/^\(.*\)$/#\1/g' /etc/fstab

Add kernel parameters [ALL]​

sudo tee /etc/modules-load.d/containerd.conf <<EOF
overlay
br_netfilter
EOF
sudo modprobe overlay
sudo modprobe br_netfilter
sudo tee /etc/sysctl.d/kubernetes.conf <<EOF
net.bridge.bridge-nf-call-ip6tables = 1
net.bridge.bridge-nf-call-iptables = 1
net.ipv4.ip_forward = 1
EOF
sudo sysctl --system

Install Containerd runtime [ALL]​

sudo apt install -y curl gnupg2 software-properties-common apt-transport-https ca-certificates
sudo curl -fsSL https://download.docker.com/linux/ubuntu/gpg | sudo gpg --dearmour -o /etc/apt/trusted.gpg.d/docker.gpg
sudo add-apt-repository "deb [arch=amd64] https://download.docker.com/linux/ubuntu $(lsb_release -cs) stable"

sudo apt update
sudo apt install -y containerd.io
containerd config default | sudo tee /etc/containerd/config.toml >/dev/null 2>&1
sudo sed -i 's/SystemdCgroup \= false/SystemdCgroup \= true/g' /etc/containerd/config.toml
sudo systemctl restart containerd
sudo systemctl enable containerd

Add apt repository for Kubernetes [ALL]​

sudo apt-get update
sudo apt-get install -y apt-transport-https ca-certificates curl gpg
curl -fsSL https://pkgs.k8s.io/core:/stable:/v1.30/deb/Release.key | sudo gpg --dearmor -o /etc/apt/keyrings/kubernetes-apt-keyring.gpg
echo 'deb [signed-by=/etc/apt/keyrings/kubernetes-apt-keyring.gpg] https://pkgs.k8s.io/core:/stable:/v1.30/deb/ /' | sudo tee /etc/apt/sources.list.d/kubernetes.list

Install Kubectl, Kubeadm, and Kubelet [ALL]​

sudo apt update
sudo apt install -y kubelet kubeadm kubectl
sudo apt-mark hold kubelet kubeadm kubectl

Initialize the cluster with Kubeadm [MASTER]​

sudo kubeadm init

To start using your cluster, you need to run the following as a regular user:

mkdir -p $HOME/.kube
sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config
sudo chown $(id -u):$(id -g) $HOME/.kube/config

Alternatively, if you are the root user, you can run:

export KUBECONFIG=/etc/kubernetes/admin.conf

You should now deploy a pod network to the cluster. Run kubectl apply -f [podnetwork].yaml with one of the options listed at Installing Addons.

Install a network plugin "Calico" [MASTER]​

kubectl apply -f https://raw.githubusercontent.com/projectcalico/calico/v3.27.3/manifests/calico.yaml

Add worker nodes [WORKER]​

kubeadm join <ip address>:6443 --token xxxxxx.xxxxxxxxxxxxxxxx \
    --discovery-token-ca-cert-hash sha256:xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx

Verify the cluster nodes [MASTER]​

kubectl get pods -A
kubectl get nodes

Deploy test application [MASTER]​

# 1. Create an NGINX pod
kubectl run nginx --image nginx

# 2. Check status
kubectl get pods --output=wide

# 3. Get a shell in the container
kubectl exec --stdin --tty nginx -- bash

# 4. Delete the container
kubectl delete pod nginx

Tips​

Mount a local dir​

deployment.yml
apiVersion: v1
kind: Pod
metadata:
  name: shell-demo
spec:
  volumes:
  - name: shared-data
    hostPath:
      path: /path/to/the/html
  containers:
  - name: nginx
    image: nginx
    volumeMounts:
    - name: shared-data
      mountPath: /usr/share/nginx/html
    ports:
    - containerPort: 80
tee /path/to/the/html/index.html <<EOF
Hello World!
EOF
kubectl apply -f deployment.yml
kubectl exec --stdin --tty mount-demo -- df
kubectl exec --stdin --tty mount-demo -- cat /usr/share/nginx/html/index.html
kubectl delete -f deployment.yml